device.hh

一个mips虚拟机非常好代码,使用C++来编写的,希望大家多学学,

#ifndef device_hh_included
#define device_hh_included

#include <assert.hh>
#include <clock.hh>
#include <bus.hh>
#include <cpu.hh>
#include <inttypes.hh>
#include <object.hh>
#include <interruptsink.hh>


// This header describes a generic memory-mapped device usable by any CPU.
// All accesses use the host byte order for addressing. The two interfaces
// return the result latency as a number of the master clock ticks. The result
// has the most significant bit set if a bus error is to be signalled.
// Finally, (0 < size <= 8). Note that all values of (size) in this range must
// be supported.

class Device
    : public Object
{
public:
    const int width;

    Bus *bus;
    InterruptSink *intctrl;

    explicit Device(int w)
	: width(w / 8) { bus = NULL; }
    virtual ClockValue read(UInt64 addr, UInt64* buf, int size) = 0;
    virtual ClockValue write(UInt64 addr, const UInt64* buf, int size) = 0;
};

// Devices signal synchronous errors through the "bus error" pin.  It is
// simulated by setting the sign bit of the returned latency.  That way,
// addition of latencies in presence of the bus error remains valid.

inline bool is_bus_error(ClockValue latency)
{
    return IntTraits<ClockValue>::Signed(latency) < 0;
}
inline ClockValue bus_error(ClockValue latency)
{
    return latency | (ClockValue(1) << (8 * sizeof(ClockValue) - 1));
}
inline ClockValue bus_latency(ClockValue latency)
{
    return bits(latency, int(8 * sizeof(ClockValue) - 2), 0);
}



#endif // device_hh_included